A reply to Mr. Robin's remarks on the Essay upon distinct and indistinct vision published at the end of Dr. Smith's Complete system of optiks / by James Jurin.
- James Jurin
- Date:
- 1739
Licence: Public Domain Mark
Credit: A reply to Mr. Robin's remarks on the Essay upon distinct and indistinct vision published at the end of Dr. Smith's Complete system of optiks / by James Jurin. Source: Wellcome Collection.
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![C s> ] the light tending to it, than is received by an¬ other fpot asg of the light tending to that, the fpot G will be comparatively dark in refpedt of the fpotg. But farther, the fimple rays of fome colours, as the citrine yellow, are much ftronger and more luminous than the reft. For this reafon, altho5 the very fame proportion of the whole of the fimple rays tending to each of thefe fpots, fhould be reflected back, but more of the citrine yel¬ low rays tending to the fpot G be refiedted, than of the fame fort of rays tending to the fpot g> ftill the former will be comparatively dark in refpedt of the latter. Now that this muft fometimes happen, that an inner fpot as G ftiall be darker than another as g more remote from the axis, will eafily ap¬ pear from what we have above demonftrated, that by means of the dilatation of every com¬ pound ray at its entering the eye, any fpot upon the retina as G will receive fimple rays from a great number of compound rays falling upon the cornea between E and D. Indeed, if the fimple rays were not endowed with different degrees of refrangibility, and therefore the compound ray CD could keep it- felf entire and unbroken all the way as it tended to the fpot G, then every fimple ray compofing it would have, 1. The fame length of paflage from the lumi¬ nous point C to the cornea at D j and mom thence to both furfaces of the cryftaliine at d and ; 2. The fame obliquity of incidence upon the cornea, and upon both furfaces of the Ciyftalline j and by this means id 2 3- The](https://iiif.wellcomecollection.org/image/b30780287_0059.jp2/full/800%2C/0/default.jpg)
